[PATCH] vhost/net: Set num_buffers for virtio 1.0

[Akihiko Odaki]

The specification says the device MUST set num_buffers to 1 if
VIRTIO_NET_F_MRG_RXBUF has not been negotiated.

Fixes: 41e3e42108bc ("vhost/net: enable virtio 1.0")
Signed-off-by: Akihiko Odaki <akihiko.od...@daynix.com>
---
 drivers/vhost/net.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index f16279351db5..d4d97fa9cc8f 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -1107,6 +1107,7 @@ static void handle_rx(struct vhost_net *net)
        size_t vhost_hlen, sock_hlen;
        size_t vhost_len, sock_len;
        bool busyloop_intr = false;
+       bool set_num_buffers;
        struct socket *sock;
        struct iov_iter fixup;
        __virtio16 num_buffers;
@@ -1129,6 +1130,8 @@ static void handle_rx(struct vhost_net *net)
        vq_log = unlikely(vhost_has_feature(vq, VHOST_F_LOG_ALL)) ?
                vq->log : NULL;
        mergeable = vhost_has_feature(vq, VIRTIO_NET_F_MRG_RXBUF);
+       set_num_buffers = mergeable ||
+                         vhost_has_feature(vq, VIRTIO_F_VERSION_1);
 
        do {
                sock_len = vhost_net_rx_peek_head_len(net, sock->sk,
@@ -1205,7 +1208,7 @@ static void handle_rx(struct vhost_net *net)
                /* TODO: Should check and handle checksum. */
 
                num_buffers = cpu_to_vhost16(vq, headcount);
-               if (likely(mergeable) &&
+               if (likely(set_num_buffers) &&
                    copy_to_iter(&num_buffers, sizeof num_buffers,
                                 &fixup) != sizeof num_buffers) {
                        vq_err(vq, "Failed num_buffers write");

---
base-commit: 46a0057a5853cbdb58211c19e89ba7777dc6fd50
change-id: 20240908-v1-90fc83ff8b09

Best regards,
-- 
Akihiko Odaki <akihiko.od...@daynix.com>